Methods and apparatus for injection molding and injection blow molding multi-layer articles, and the articles made thereby

Abstract

An apparatus for injection molding a plurality of multilayer, multimaterial plastic containers. A plurality of co-injection nozzles are positioned to feed a plurality of cavities defined by a plurality of injection molds and a source of polymer materials is located upstream of the nozzles. The apparatus also includes a flow channel for each of a plurality of polymer streams to define a path between the polymer source and at least one of the co-injection nozzles such that each of the co-injection nozzles is in communication with one of the flow channels for each polymer stream and the polymer streams enter more than one of the co-injection nozzles. The channels are arranged to provide substantially the same flow experience to each polymer stream.

What is claimed is: 
     
       1. Apparatus for injection molding a plurality of multilayer, multi-material plastic containers, which comprises: a plurality of injection molds which define injection cavities,   a plurality of juxtaposed co-injection nozzles positioned to feed the cavities of the injection molds,   a source of polymer materials located upstream of the nozzles, said source of polymer materials creating multiple polymer streams, each of said polymer streams corresponding to at least one layer of said plurality of containers,   means defining a flow channel for each polymer stream, each flow channel defining a path between said source and at least one of said co-injection nozzles such that each of said co-injection nozzles is in communication with one of said flow channels for each said polymer stream, wherein said polymer streams enter more than one of said co-injection nozzles;   each of said flow channels being separate and having a portion providing substantially the same flow experience for one of said polymer streams entering more than one of said co-injection nozzles.   
     
     
       2. Apparatus according to claim 1, characterized in the moving means and channeling means therefrom are operative to subject corresponding material streams entering the plural nozzle means to substantially identical flow conditions. 
     
     
       3. Apparatus according to claim 1 wherein the apparatus includes means to effect substantially simultaneous flow or non-flow of polymer material from said co-injection nozzles. 
     
     
       4. Apparatus for injection molding a plurality of multilayer, multi-material thin plastic containers which comprises, a plurality of injection molds which define injection cavities,   a plurality of juxtaposed co-injection nozzles positioned to feed the injection cavities of the injection molds,   a source of polymer materials located upstream of the nozzles, said source of polymer materials creating a polymer stream for each of said materials which is to form at least one layer of said plurality of containers,   means for moving each polymer stream of each material which is to form at least one layer of said plurality of containers,   means defining a flow channel for each polymer material which is to form at least one layer of said plurality of containers, there being a flow channel for each said material in communication with said source, said moving means and at least one of said co-injection nozzles, such that each of said co-injection nozzles is in communication with a flow channel for each said material,   each of said flow channels being separate and providing substantially the same polymer flow for one portion of polymer material in its path from said moving means to one of said co-injection nozzles as is provided for each other portion of said polymer material in its path to another of said co-injection nozzles.   
     
     
       5. The apparatus of claim 4 wherein the apparatus includes a separate passageway in each of said co-injection nozzles for each polymer material which is to form at least one layer of one of said containers, each of said passageways communicates with the appropriate flow channel for each polymer material which is to form at least one layer of one of said containers, and the length of each passageway and its communicating flow channel extending from said moving means to one of said co-injection nozzles for one of said polymer streams is substantially the same as that for each other polymer stream of the same material which is to be injected from each other of said co-injection nozzles and which is to form at least one corresponding layer in each other container. 
     
     
       6. The apparatus of claim 4, characterized in the moving means and channeling means therefrom are operative to subject corresponding material streams entering the plural nozzle means to substantially identical flow conditions. 
     
     
       7. Apparatus according to claim 4 wherein the apparatus includes means to effect substantially simultaneous flow or non-flow of polymer material from said co-injection nozzles. 
     
     
       8. Apparatus for injection molding a plurality of multilayer, multi-material plastic containers having at least three layers, including two surface layers and an internal layer between the surface layers, which comprises: a plurality of injection molds which define injection cavities, mounted on one member,   a plurality of juxtaposed co-injection nozzles mounted on a juxtaposable member, wherein each co-injection nozzle has an open end, a gate at the open end, a cylindrical injection path in communication with and through the gate, and a plurality of polymer material fixed passageways each having a fixed orifice substantially in communication with the injection path, the passageway for the internal layer having a frustoconical tapered portion adjacent its orifice,   means for juxtaposing and abutting the co-injection nozzles with the cavities of the injection molds,   a source of polymer materials located upstream of the nozzles, said source of polymer materials creating a polymer stream for each of said materials which is to form at least one layer of said plurality of containers,   means for moving each polymer stream of each said material which is to form at least one layer of said plurality of containers,   means defining a flow channel in communication with said source and said moving means for each polymer material which is to form at least one layer of said plurality of containers, each flow channel for each material communicating with said source, said moving means and at least one of said co-injection nozzles, such that each of said co-injection nozzles is in communication with a flow channel for each said material,   each of said flow channels being separate and the means defining the flow channel extending from said moving means to one of said co-injection nozzles being adapted to provide substantially the same flow for the polymer material entering each of said co-injection nozzles and which is to form the two surface layers, and to provide substantially the same flow for the polymer material entering each of said co-injection nozzles and which is to form the internal layer of each of said plurality of containers.   
     
     
       9. The apparatus of claim 8 wherein the means defining the flow channels for providing substantially the same flow, minimize the differences in the flow history of each portion of the same of said polymer materials which is channeled to each co-injection nozzle. 
     
     
       10. Apparatus for injection molding a plurality of containers, each container having at least a first layer of a first polymer material and a second layer of a second polymer material, wherein said first polymer material is different from said second polymer material, said apparatus comprising: a plurality of injection molds which define injection cavities;   a plurality of co-injection nozzles, each of said nozzles positioned to inject said first and second materials into said cavities;   first and second sources of polymer materials for said first polymer material and said second polymer material, respectively, both located upstream of said co-injection nozzles;   said first and second sources of polymer materials creating first and second polymer streams, respectively;   said first and second polymer streams each having portions which enter each of said co-injection nozzles;   first and second flow channels for providing said first and second polymer materials, respectively, to each of said co-injection nozzles, each flow channel for each polymer material communicating with one of said first and second sources of polymer material and each of said co-injection nozzles such that each of said co-injection nozzles is in communication with said flow channel for each polymer stream of material; and   said first flow channel being separate from said second flow channel and having a portion providing substantially the same flow experience for each portion of said first polymer stream entering each of said co-injection nozzles.   
     
     
       11. The apparatus of claim 10 wherein said second flow channel having a portion providing substantially the same flow experience for each portion of said second polymer stream entering each of said co-injection nozzles. 
     
     
       12. The apparatus of claim 11 wherein said first polymer material is polyethylene terephthalate. 
     
     
       13. The apparatus of claim 12 wherein said second polymer material is an oxygen-barrier material. 
     
     
       14. The apparatus of claim 13 wherein said second polymer is ethylene vinyl alcohol.